What is its difference with fixedvalue in application?
in its .h description it says:

HTML Code:

Description
Inlet velocity in which the actual interstitial velocity is calculated
by dividing the specified inletVelocity field with the local phase-fraction.

To find its difference with uniformFixedValue I compared average magnitude of inlet velocity (By using Integration over bottom patch) and found that in fixedvalue (0 0 2) the average of inlet velocity is 2, But in interstitialInletVelocity of ( 0 0 2 ) the average velocity is 4.8 m/s.
I calculated average alpha.air magnitude in this patch = 0.42 and understood that 4.8 m/s=2.0/0.42 as described in .h file.
Seeing the contour of inlet in this condition shows the magnitude of air varies between 4 to 6.51 m/s with the average of 4.89 (is attached) and I don't know why it increases the stated 2 m/s to higher magnitudes. If it considers the solid fractions in inlet patch so it should be some zero magnitude velocities on inlet but there is not seen.

The logic might be that the phase proportion is inversely proportional to the velocity, possibly due to a vacuum-like effect. I.e., when there is very little of this phase (smaller than 1.0), it acts as high-speed+low-pressure combination.

. It seems that this is always used in the inlet BC of continuous phase. So in this case, the item 'inletVelocity' corresponds to the actual velocity predicted from the mass flow rate? So the inlet velocity which is from 'inletVelocity / alpha' is always bigger than the actual one. Do we also need to use this BC for the dispersed phase inlet BC? Thank you so much.